1284
SIR,-Dr Newton and colleagues describe raised intracranial pressure in Kenyan children with cerebral malaria. We have seen a severe falciparum malaria and coma who had an opening cerebrospinal fluid (CSF) pressure of 40 cm water. A mannitol infusion resulted in striking improvement in cerebral
How well do
sunglasses protect against ultraviolet radiation?
white adult with
status.
A 61-year-old man, just returned from West Africa, was admitted hospital with a 2 week history of fever and myalgia. P falciparum parasitaemia was 2% of red cells. He was treated with oral chloroquine 900 mg over 12 h, after which he had 20% parasitaemia. On transfer to intensive care the patient was jaundiced and febrile but fully alert without neurological abnormality. He was thrombocytopenic (9000/1) with a slightly prolonged prothrombin time (but no evidence of disseminated intravascular coagulation), mild azotaemia, and hyponatraemia. Blood glucose was normal. Intravenous quinine was started, with monitoring to maintain levels (at 18-30 pmol/1). After 12 h, he had passed only 50 ml of black urine, and his urea and creatinine had risen sharply (to 318 mmol/l, and 368 pmol/1. Parasitaemia remained at 20%. Haemofiltration and a 6 unit exchange transfusion reduced the parasitaemia to 6%. On the following day parasitaemia was 2% and haematological and biochemical indices were stabilising. However, the patient’s conscious level deteriorated. He became aphonic and failed to localise to pain. Plantar reflexes were extensor. The pupils were equal and reacted to light and the fundi appeared normal. A computed tomographic (CT) scan showed no evidence of cerebral oedema or hydrocephalus.CSF opening pressure was 40 cm water. CSF protein, glucose, and cell counts were within normal limits, no organisms were cultured from CSF or blood, and there was no other obvious reason for the coma. Two infusions of 100 ml 20% mannitol 8 h apart were given with a dopamine infusion to maintain cerebral perfusion. Quinine was continued and the parasitaemia continued to fall. Continuous measurement of CSF pressure was contraindicated by the patient’s low platelet count. Over the next 12 h his conscious state improved and he made a full recovery, though haemodialysis for 30 days was needed before renal function returned. The development of coma some 24 h after peak parasitaemia is not unusual in cerebral malaria, possibly because sequestered parasites are cleared more slowly from brain than blood. The high CSF pressure with a normal CT scan supports the notion that raised intracranial pressure may be important in the pathogenesis of cerebral malaria in adults. Mannitol, with cerebral pressure monitoring where possible, may be beneficial. Mannitol is listed among treatments for cerebral malaria not recommended by the WHO Malaria Action Programmed No adequate trials have been done, but improved survival was suggested in a small series of West African children with cerebral malaria who were treated with osmotic diuretics2 (3% urea in 10% invert sugar) when they did not improve with chloroquine. 3 of 5 children who did not receive osmotic diuretics died while there were no deaths in 10 patients who did. Studies using mannitol as well as dexamethasone in cerebral malaria also showed low mortality3 but enthusiasm for steroid treatment waned when controlled trials showed that it was harmful.4,5 Similar trials of osmotic diuretics are needed in cerebral malaria. to
We thank Dr A. P. Hall for
allowing publication of this case.
SIR,--Contradictory reports on the protective effects of sunglasses from solar ultraviolet (UV) radiation1.2 have caused some confusion among ophthalmologists when advising patients. Medical advice is often sought because department stores offer sunglasses at bargain prices, and because an increase in solar LTVB radiation in the Alps3 has been reported after stratospheric ozone depletion.4 Two questions arise: does a high price guarantee UV protection, and are cheap sunglasses less effective? Solar UV radiation may cause acute photokeratitis (snowblindness)5 and can promote cataract formationOnly UVB radiation (280-320 nm) contributes to photokeratitis, and UVB is a more important influence in cataract generation than UVA (320-400 nm). We tested a random collection of sunglasses (30 different makes and prices) for spectral UV transmission with a high resolution double monochromator. The figure gives examples of measured spectral transmissions to document the range of variation. All tested sunglasses filtered solar LTVB radiation completely. No danger to the eyes would be expected from UVB radiation when sunglasses are worn. Transmissions of UVA radiation varied greatly. Transmission measured up to 75 % at 390 nrn, and the wavelength of cutoff ranged from 340 and 410 nm. There was no link between price and UVA transmission.
Spectral transmission data. Results from five sunglasses are shown 1 and 2 show especially good UVA protection 1 was very cheap and 2 was expensive The other sunglasses are in the medium price range.
Transmission values are measured with broadband UV detectors
by manufacturers, but have only limited suitability for evaluating UVA protection. Spectral UV transmission data are more informative and should be more widely available. This issue is important because of the large rise in numbers of Alpine skiers exposed to increased UV radiation. In these cases, additional protection against lateral incident radiation is recommended to shelter the eyes from diffuse UV radiation.
Hospital for Tropical Diseases, London NW1 0PE, UK
HUMPHREY D. L. BIRLEY DAVID C. W. MABEY
University College and Middlesex School of Medicine, London WC1
MERVYN SINGER
1. Warrell DA, Molyneux ME, Beales PF, eds. Severe and complicated malaria, 2nd ed. Trans R Soc Trop Med Hyg 1990; 84 (suppl). 2. Kingston ME. Experience with urea in invert sugar for the treatment of cerebral malaria. J Trop Med Hyg 1971; 74: 249-52. 3. Commey JO. Is it cerebral malaria? Lancet 1984; ii: 1037. 4. Warrell DA, Looareesuwan S, Warrell MJ, et al. Dexamethasone proves deleterious in cerebral malaria: a double-blind trial in 100 comatose patients. N Engl J Med 1982; 306: 313-19. 5. Hoffman SL, Rustama D, Punjabi N, et al. High dose dexamethasone in quinine treated patients with cerebral malaria: a double-blind, placebo-controlled trial. J Infect Dis 1988; 158: 325-31.
Institute of Medical Physics, University of Innsbruck, A-6020 Innsbruck, Austria
1 Rosenthal
M. BLUMTHALER W. AMBACH
FS, Bakalian AE, Taylor HR. The effect of prescription eyewear on ocular exposure to ultraviolet radiation. Am J Publ Health 1986, 76: 1216-20, 2. Hoover HL. Sunglasses, pupil dilation, and solar ultraviolet irradiation of the human lens and retina. Appl Opt 1987; 26: 689-95. 3. World Meterological Organisation. Executive summary of the ozone trends panel Geneva: WMO, 1988. 4. Blumthaler M, Ambach W. Indication of increasing solar ultraviolet-B radiation flux in alpine regions. Science 1990; 248: 206-08. 5.Pitts DG The ocular effect of ultraviolet radiation Am J Optom Physiol Opt 1978, 55: 19-35. 6. Taylor HR, West SK, Rosenthal FS, et al. Effect of ultraviolet radiation on cataract formation. N Engl JMed 1988; 319: 1429-33.
SIR,-Dr Newton and colleagues describe raised intracranial pressure in Kenyan children with cerebral malaria. We have seen a severe falciparum malaria and coma who had an opening cerebrospinal fluid (CSF) pressure of 40 cm water. A mannitol infusion resulted in striking improvement in cerebral
How well do
sunglasses protect against ultraviolet radiation?
white adult with
status.
A 61-year-old man, just returned from West Africa, was admitted hospital with a 2 week history of fever and myalgia. P falciparum parasitaemia was 2% of red cells. He was treated with oral chloroquine 900 mg over 12 h, after which he had 20% parasitaemia. On transfer to intensive care the patient was jaundiced and febrile but fully alert without neurological abnormality. He was thrombocytopenic (9000/1) with a slightly prolonged prothrombin time (but no evidence of disseminated intravascular coagulation), mild azotaemia, and hyponatraemia. Blood glucose was normal. Intravenous quinine was started, with monitoring to maintain levels (at 18-30 pmol/1). After 12 h, he had passed only 50 ml of black urine, and his urea and creatinine had risen sharply (to 318 mmol/l, and 368 pmol/1. Parasitaemia remained at 20%. Haemofiltration and a 6 unit exchange transfusion reduced the parasitaemia to 6%. On the following day parasitaemia was 2% and haematological and biochemical indices were stabilising. However, the patient’s conscious level deteriorated. He became aphonic and failed to localise to pain. Plantar reflexes were extensor. The pupils were equal and reacted to light and the fundi appeared normal. A computed tomographic (CT) scan showed no evidence of cerebral oedema or hydrocephalus.CSF opening pressure was 40 cm water. CSF protein, glucose, and cell counts were within normal limits, no organisms were cultured from CSF or blood, and there was no other obvious reason for the coma. Two infusions of 100 ml 20% mannitol 8 h apart were given with a dopamine infusion to maintain cerebral perfusion. Quinine was continued and the parasitaemia continued to fall. Continuous measurement of CSF pressure was contraindicated by the patient’s low platelet count. Over the next 12 h his conscious state improved and he made a full recovery, though haemodialysis for 30 days was needed before renal function returned. The development of coma some 24 h after peak parasitaemia is not unusual in cerebral malaria, possibly because sequestered parasites are cleared more slowly from brain than blood. The high CSF pressure with a normal CT scan supports the notion that raised intracranial pressure may be important in the pathogenesis of cerebral malaria in adults. Mannitol, with cerebral pressure monitoring where possible, may be beneficial. Mannitol is listed among treatments for cerebral malaria not recommended by the WHO Malaria Action Programmed No adequate trials have been done, but improved survival was suggested in a small series of West African children with cerebral malaria who were treated with osmotic diuretics2 (3% urea in 10% invert sugar) when they did not improve with chloroquine. 3 of 5 children who did not receive osmotic diuretics died while there were no deaths in 10 patients who did. Studies using mannitol as well as dexamethasone in cerebral malaria also showed low mortality3 but enthusiasm for steroid treatment waned when controlled trials showed that it was harmful.4,5 Similar trials of osmotic diuretics are needed in cerebral malaria. to
We thank Dr A. P. Hall for
allowing publication of this case.
SIR,--Contradictory reports on the protective effects of sunglasses from solar ultraviolet (UV) radiation1.2 have caused some confusion among ophthalmologists when advising patients. Medical advice is often sought because department stores offer sunglasses at bargain prices, and because an increase in solar LTVB radiation in the Alps3 has been reported after stratospheric ozone depletion.4 Two questions arise: does a high price guarantee UV protection, and are cheap sunglasses less effective? Solar UV radiation may cause acute photokeratitis (snowblindness)5 and can promote cataract formationOnly UVB radiation (280-320 nm) contributes to photokeratitis, and UVB is a more important influence in cataract generation than UVA (320-400 nm). We tested a random collection of sunglasses (30 different makes and prices) for spectral UV transmission with a high resolution double monochromator. The figure gives examples of measured spectral transmissions to document the range of variation. All tested sunglasses filtered solar LTVB radiation completely. No danger to the eyes would be expected from UVB radiation when sunglasses are worn. Transmissions of UVA radiation varied greatly. Transmission measured up to 75 % at 390 nrn, and the wavelength of cutoff ranged from 340 and 410 nm. There was no link between price and UVA transmission.
Spectral transmission data. Results from five sunglasses are shown 1 and 2 show especially good UVA protection 1 was very cheap and 2 was expensive The other sunglasses are in the medium price range.
Transmission values are measured with broadband UV detectors
by manufacturers, but have only limited suitability for evaluating UVA protection. Spectral UV transmission data are more informative and should be more widely available. This issue is important because of the large rise in numbers of Alpine skiers exposed to increased UV radiation. In these cases, additional protection against lateral incident radiation is recommended to shelter the eyes from diffuse UV radiation.
Hospital for Tropical Diseases, London NW1 0PE, UK
HUMPHREY D. L. BIRLEY DAVID C. W. MABEY
University College and Middlesex School of Medicine, London WC1
MERVYN SINGER
1. Warrell DA, Molyneux ME, Beales PF, eds. Severe and complicated malaria, 2nd ed. Trans R Soc Trop Med Hyg 1990; 84 (suppl). 2. Kingston ME. Experience with urea in invert sugar for the treatment of cerebral malaria. J Trop Med Hyg 1971; 74: 249-52. 3. Commey JO. Is it cerebral malaria? Lancet 1984; ii: 1037. 4. Warrell DA, Looareesuwan S, Warrell MJ, et al. Dexamethasone proves deleterious in cerebral malaria: a double-blind trial in 100 comatose patients. N Engl J Med 1982; 306: 313-19. 5. Hoffman SL, Rustama D, Punjabi N, et al. High dose dexamethasone in quinine treated patients with cerebral malaria: a double-blind, placebo-controlled trial. J Infect Dis 1988; 158: 325-31.
Institute of Medical Physics, University of Innsbruck, A-6020 Innsbruck, Austria
1 Rosenthal
M. BLUMTHALER W. AMBACH
FS, Bakalian AE, Taylor HR. The effect of prescription eyewear on ocular exposure to ultraviolet radiation. Am J Publ Health 1986, 76: 1216-20, 2. Hoover HL. Sunglasses, pupil dilation, and solar ultraviolet irradiation of the human lens and retina. Appl Opt 1987; 26: 689-95. 3. World Meterological Organisation. Executive summary of the ozone trends panel Geneva: WMO, 1988. 4. Blumthaler M, Ambach W. Indication of increasing solar ultraviolet-B radiation flux in alpine regions. Science 1990; 248: 206-08. 5.Pitts DG The ocular effect of ultraviolet radiation Am J Optom Physiol Opt 1978, 55: 19-35. 6. Taylor HR, West SK, Rosenthal FS, et al. Effect of ultraviolet radiation on cataract formation. N Engl JMed 1988; 319: 1429-33.
